Published online by Cambridge University Press: 14 January 2011
The depth profiles of the constituent in iron oxide scales were investigated by X-ray diffraction measurement with controlling X-ray penetration depth at SPring-8. We successfully observed the interface region of scales non-destructively using X-ray with energy of 28 keV. The results indicated that the volume fraction ratio of Fe3O4 to FeO around the surface of samples increased by isothermal heat treatment. This suggested that the transformation of FeO to Fe3O4 due to isothermal heat treatment proceeds from surface into the inside of scale.